2001 Challenger 2000 Engine Bogged Down While Underway

[kurly]

240 EFI engine, manufactured Feb 2001. Reliable engine for the past two years I've owned the boat. Always started and ran with no problems. Took the boat out for the third or fourth time this season. About a mile out from the launch, I reduced throttle as I approached some wake and the engine bogged down. I increased the throttle and it sounded like the engine was overloaded (exhaust tone sounded deeper) and the RPM would not increase. Thought I had sucked something into the jet drive. I limped back to the dock with the engine at about 2000 RPM and when I cut back the throttle to idle to maneuver at the launch, the engine died. Got the boat back on the trailer and inspected the intake, nothing visible in the jet. Started the boat at home on the hose to flush it out. Ran for about 5 minutes at idle then died.

So, started down the checklist of simple stuff:
1. Pulled and replaced spark plugs. All looked about the same, black residue with a slight wetness. Nothing burned or cracked, or overly worn.
2. Replaced inline fuel filter at the electric fuel pump.
3. Replaced water separating fuel filter.
4. Checked battery voltage (12.1V). Had the battery charged (12.6V) and load tested. Came back good according to the tester at the auto parts store.

Attempted to start motor again on hose. Ran the fuel pump before engaging the starter to refill the fuel system. Engine starts, runs for a few seconds, then dies. Any ideas for next steps?

Thanks.

 

[Dr Honda]

With any 2 stroke engine... I always start with a compression check.

But, it could be a bad high-pressure pump, a bad regulator, or a bunch of other things at this point.

By any chance... when you had the spark plugs out... did you try to turn the engine over by hand?

 

[kurly]

Thanks for the response. I did not try to turn the engine over with the spark plugs out. Suggestions for next steps? I have no problem troubleshooting or digging into the details, just need to have an idea where to look next.

 

[Dr Honda]

Compression first. No reason to even look for something else until we know the engine is healthy. I'd like to see 120 psi or better.

 

[kurly]

110 PSI all six cylinders.

 

[Dr Honda]

Low... but it should run.

OK.. let's move onto fuel.

Make sure the pulse pump is connected, and pumping. Make sure the electric lift pump is working. Then... you will want to get a pressure gauge on the high pressure rail.

 

[kurly]

Thanks for the prompt assistance and guidance, Tony. I've located a local shop that is "non-denominational" (works on SeaDoo jet boats regardless of their power source). I'm going to take the boat to them for service.

 

[ctc1111]

Have you had any luck fixing the issue? Or has your mechanic diagnosed the issue? I am having very similar problems with my boat which is the same year, same boat, and engine.

 

[poocool]

check for spark

 

[kurly]

Update - Long summer with no boat . . . Shop replied with a mixed diagnoses of water in fuel, fuel system components showing age, trigger coil for one bank out of spec. Shop drained and cleaned the fuel system, replaced electric fuel pump, replaced trigger coil, and returned the boat to me. Two more trips back to correct fuel leaks and finally took a boat ride this weekend. Now, the boat starts and will run.

Latest symptoms are:
1. Low idle - engine will stall if not shifted out of neutral and throttle increased.
2. Copious blue smoke on idle and while underway - previously some smoke only on startup and no noticeable smoke while underway.
3. Burning lots of fuel while underway.
4. Engine only really runs smoothly near WOT.

Seems like the throttle position sensor (TPS) is the next place to look?

 

[Dr Honda]

The TPS is $500. BUT... the port side head, temp sensor will cause the same issues. Check it first, and...

1) Make sure it's hooked up properly. (just saying since they worked on the electrical)
2) Make sure it's working.

At the top of the forum page... there is a sticky saying "Best tune-up." Look at it for diagnostic, and part numbers.

 

[kurly]

Visually inspected the port side head temp sensor and looked intact with all connections firm and matched by wire color. Removed the sensor and tested resistance across the tan/black sensor leads, 0.1 ohms with the sensor at 85 deg F. Placed the metal end of the sensor in ice water and monitored resistance for a couple of minutes. No change in resistance with the water temperature at 45 deg F. According to the service manual, the resistance at 45 deg F should be ~2.3 k-ohm at 45 deg. So, a new port side head temp sensor is the next step?

 

[Dr Honda]

Yep. Sounds like yours has gone bad.

When I did my rebuild... I bought a new one, even though my old one was still good. But, since they randomly die... and cause all kinds of running issues when they give up... I figured it was best to have one in the tool box.

When you put in the new one... make sure you put some fresh grease down in the hole. (For thermal transfer)

I get parts like that from Boats.net ($31) but if you have a local shop... I think they are only about $38.

http://www.boats.net/parts/detail/merc/M-13536A14.html

 

[kurly]

Replaced port head temp sensor. Now engine idles at ~1100 on cold start then comes down to ~1000 when warm. Little blue smoke now when idling on the hose, but . . . when I shut the boat down and looked around back, there was black oil residue on the ground under the exhaust outlets.

Low oil warning light is on now also. Checked reservoir and tank, both have oil in them. Moved the float up and down, light stays on and no warning horn. The warning horn does beep on startup as usual.

 

[Dr Honda]

Black oil is normal when it sits. Also... whit your low compression... you aren't going to burn all your oil. With that said... I would verify the oil pump position at idle.


As far as the oil warning... sounds like you popped a wire off somewhere while working on the boat. Also... your boat has 2 buzzers, so make sure both work. (one was dead in my islandia)

 

[kurly]

Took the boat out for a test on the water over the weekend, definitely a happier engine. Warmed up at the dock, ran a little rough initially on acceleration. Smoothed out after about a minute. Accelerated and decelerated smoothly after that. Idled for maneuvering at the dock without stalling. Thanks for all of the help, Tony.